Forum Discussion
Monty_152734
Nimbostratus
NimbostratusIncrease TPS per host IP
Hi,
Our team is asking me to increase TPS per host IP from 30 to 90. They provided me an irule which is currently serving. According to team, this irule is limited for 30 TPS per host IP and I need to find right value for "maxRate, timeout and related" Can someone please help me in the modification of this rule and also explain what this irule do (step by step)? it will be really very helpful. Thanks in advance
when RULE_INIT {
set static::maxRate 900 * 3
set static::windowSecs 1
set static::timeout 30 }
when HTTP_REQUEST {
if { [HTTP::method] eq "GET" } {
set getCount [table key -count -subtable [IP::client_addr]]
log local0. "getCount=$getCount"
if { $getCount < $static::maxRate } {
incr getCount 1
table set -subtable [IP::client_addr] $getCount "ignore" $static::timeout $static::windowSecs
} else {
log local0. "Exceeded the number of requests allowed. $getCount"
HTTP::respond 501 content "Request blockedExceeded requests/sec limit."
return
} } }
What version of BIG-IP are you running, please?
Monty_152734Thanks for the reply. we are running BIG-IP 12.1.2 Build 0.93.249
Before I try to analyze further, the iRule does not save properly on my 12.1 system. A syntax error is generated on the first command - set static::maxRate 900 * 3. Is the intent of that command to set the maxRate to 2700? Also, what sort of log messages are you seeing with respect to current counts?
- Monty_152734
Yes, you are right. The intent is to set maxRate to 2700 as the team wants 90 TPS so I believe the calculation would be maxRate/timeout = TPS (2700/30 = 90TPS). Am I right?
My understanding is that a subtable entry is removed when either the timeout or lifetime value is reached, whichever comes first. Since lifetime (static::windowSecs = 1) is less than timeout (static::timeout = 30), no matter how many times a particular subtable entry is touched via the TABLE SET command (which resets the timeout value on the subtable entry), the entry will be removed after 1 second due to the lifetime. And since your sliding window for counting max TPS is 1 second, that makes sense. The question is how does the 2700 maxRate fit into this. That is why I was interested in seeing the log messages this iRule currently produces. Are you ever getting the custom 501 log page and, if so, what is the count in the associated log message? Is it 30 (or 90) or something else?
